Physiological effects of caffeine, epigallocatechin-3-gallate, and exercise in overweight and obese women
Journal Title (Medline/Pubmed accepted abbreviation): Appl Physiol Nutr Metab
Year: 2010
Volume: 35
Page numbers: 607-616
doi: 10.1139/H10-056

Summary of Background and Research Design

Background: Obesity is the result of a positive energy balance and contributes to more than 300,000 deaths per year. Recent research has been particularly focused on the use of plant compounds (ie, caffeine, green tea), with a principal aim of reducing food intake and/or increasing energy expenditure. Green tea is a widely consumed beverage that contains substantial amounts of catechins, including the most abundant—epigallocatechin-3-gallate (EGCG). Although caffeine and EGCG formulas have been effective in increasing fat oxidation and energy expenditure in healthy individuals, the effects in an overweight population with moderate exercise and an unrestricted diet have not been examined.

Hypothesis/purpose of study:To evaluate the combined effects of a 10-week exercise program and chronic ingestion of a drink containing caffeine and EGCG on body composition, cardiovascular fitness, strength, and safety in overweight and obese women

Subjects: Twenty-seven sedentary (< 30 minutes of physical activity per week) women (mean ± standard deviation: age 27.3 ± 8.6 yr, weight 74.3 ± 11.3 kg, height 164.7 ± 8.1cm, percentage of body fat 38.1% ± 2.9%) were randomly assigned to treatment groups with exercise (an active-supplementing group with exercise [EX-Act] and a placebo group with exercise [EX-PL]) or without exercise (an active-supplementing group without exercise [NEX-Act] and a placebo group without exercise [NEX-PL]).

Experimental design: Double-blind, randomized, placebo-controlled study

Treatments and protocol: All participants consumed 1 drink per day for 70 consecutive days. The active drink consumed by subjects in the EX-Act and NEX-Act groups consisted of 10 kcal, vitamins B6 and B12, and a blend of taurine, guarana extract, green tea leaf extract (EGCG), caffeine, glucuronolactone, and ginger extract. The placebo drink consisted of the same calorie and vitamin content without the active caffeine and EGCG blend. Subjects in exercise groups (EX-Act and EX-PL) participated in a concurrent endurance and resistance training program 15 to 35 minutes per day, 5 days per week, and consumed 1 drink 15 minutes prior to all exercise sessions (resistance training was done twice per week). Changes in fat mass (FM) and fat-free mass (FFM) were assessed using a 4-compartment model on the same day following a 12-hour fast. Changes in muscle mass (MM) were evaluated using a dual-energy x-ray absorptiometry-derived appendicular lean–soft tissue equation. Cardiorespiratory measurements—peak oxygen consumption (VO2peak), ventilator threshold (VT), baseline blood pressure and resting heart rate were obtained. Upper-body and lower-body strengths were assessed using bench and incline leg presses, respectively. The resulting strength values were used to establish individualized resistance-training programs. Serum and whole-blood samples were used to evaluate clinical safety during the study. All samples were assayed for comprehensive metabolic panels and blood lipids.

Summary of research findings:
  • Diet was not controlled in this study, but dietary records obtained weekly over the 11 weeks showed no differences in energy, carbohydrate, protein, or fat intake among the treatment groups.
  • With regard to MM, there was no significant effect of the drink. However, there was an effect of the exercise, as the EX-Act and EX-PL groups experienced similar gains in MM.
  • Similar to the results for MM, both the EX groups had comparable gains in FFM (1.3 to 2.0 kg) and there were no effects of the drink. There were no significant changes observed for FM or % body fat among the treatment groups.
  • There was a significant time × training interaction (P < .05) for VO2peak, but post-hoc analyses demonstrated no significant differences between training groups.
  • Both EX groups demonstrated a significantly greater increase in VT from pretesting to posttesting compared with the NEX groups, but there was no significant difference between dietary treatment groups.
  • Resting heart rate and blood pressure demonstrated no significant change for any group.
  • Upper-body and lower-body strength improved significantly for EX-Act (13.26% and 27.81%) and EX-PL (20.49% and 26.97%) but there were no changes in the NEX groups.
    • The strength increases for both upper and lower body strength were not different between the EX-Act and EX-PL conditions, indicating no specific effect of the drink.
  • Total blood cholesterol was significantly decreased only in the EX-Act group, whereas both EX-Act and NEX-Act groups demonstrated a significant reduction in LDL values (12.5% and 18.4%, respectively) with no change in HDL.
    • Triglycerides went up significantly in the EX-Act group only but were still within the normal clinical range.
  • The blood panel results demonstrated no deleterious effects from elongated consumption of the caffeine-EGCG blend on any of the clinical safety markers examining hepatic, renal, cardiovascular, and immune function.
    • Other than the blood lipid changes already mentioned, no significant changes were apparent for any blood or serum variables over time for any of the groups.

Interpretation of findings/Key practice applications:

In this study, a drink containing a blend of caffeine, EGCG, and other compounds had no significant effects on body composition, strength, ventilatory threshold, resting heart rate, and resting blood pressure when fed once per day for 70 consecutive days. There were, however, potentially beneficial reductions in LDL cholesterol in both the EX-Act and NEX-Act groups. It is also noteworthy that there were no safety concerns associated with ingestion of this drink daily for 70 days in a population of overweight women. A couple of key limitations of this study are that the diet of the subjects was not controlled or reduced in energy and there was no information on other doses of this drink.
Note of caution: The data presented in Figure 1 of this article on body composition could not be reconciled by two reviewers with the text in the “Body Composition” section of the Results or Table 3 in this paper.  For example, Figure 1 shows an overall decrease in muscle mass in the EX-PL group and an overall increase in muscle mass in the NEX-PL group, findings that would ordinarily not be expected. This is contrary to the results reported in Table 3 in which there was significant increase in muscle mass in the EX-PL group and a non-significant decrease in muscle in the NEX-PL group.  This and other discrepancies may raise significant overall questions regarding the validity of the data presented.
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